That P is intuitive makes P probable?

Maybe there is a huge literature out there about intuition (or rational insight) as a source of justification and knowledge – but I didn’t read any paper on it yet. However, I have a promissory note to deal with questions surrounding this cognitive power. The fact is that every time I read a philosopher accepting or rejecting a certain thesis on the basis that it is intuitive or counter-intuitive, I feel uncomfortable. So, I’ll try to explain why that is so. At the same time, I would like to know if the reader of this post feels completely assured that intuition is a good source of justification and knowledge (you can feel comfortable to indicate papers dealing with this question).

Doubts surrounding intuition can arise when one is in the context of philosophical discourse. In such context, it is usual to present philosophical analyzes by means of propositions with the form:

x is if, and only if, x is B,

or:

is only if is B

where ‘A’ and ‘B‘ are predicates standing for relations and properties (or sets of relations and/or properties). Generally, it is said that beliefs in such propositions are justified a priori – by means of reasoning from justified premises, or by means of understanding the meanings of ‘A’ and ‘B’, or then by means of rational intuition. It seems it is not as clear how such beliefs are justified by intuition as it is when they are justified by reasoning and linguistic understanding – what is a rational intuition? What epistemic properties it has?

Nevertheless, philosophers in general make use of intuition to refute and endorse propositions with that form. The theoretical procedure of endorsing a proposition by means of intuition can be represented by the following argument-type:


(i) It is intuitive that x is only if x is B

(ii) Therefore, is only if is B


This argument-type is instantiated by, for example:


(i’) It is intuitive that, if S knows that P, then S has some degree of certainty with respect to P

(ii’) therefore, if knows that P, then has some degree of certainty with respect to P


In a similar way, there is a theoretical procedure in which one refutes a proposition by means of intuition that can be represented by the following argument-type:


(iii) It is counter-intuitive that x is A when x is B

(iv) Therefore, x is not A when x is B


This argument-type is instantiated by, for example:


(iii’) It is counter-intuitive that S has knowledge when S has a justified belief which is accidentally true

(iv’) Therefore, S does not have knowledge when S has a justified belief which is accidentally true


What kind of argument is that authorizing the passage from (i) to (ii) and from (iii) to (iv)? Clearly, the argument is not a valid one: it is possible for the conclusion to be false while the premise is true. It can perfectly be the case that P is intuitive and false, as it can perfectly be the case that P is counter-intuitive and true.

But there is another option for taking these arguments as good ones (that is, not ill-formed): they are inductively strong (or cogent as Feldman calls it in Reason & Argument). In that case, the thesis is as follows:


(IN) If it is intuitive that P, then P is probably the case


And, if (IN) is the case, the following epistemic norm can be derived:


(ENI) When P is intuitive to S, S is epistemically insured in believing that P


This epistemic norm does not require S to know/justifiably believe that (IN) is the case – intuition can play its justificatory role even if neither (IN) nor (ENI) are actually accessed by S. The worry about the epistemic status of (IN) is part of the epistemologist job, however, which wants to justify the epistemic norm (ENI). Now, my question is: how can the epistemologist justify (IN)? What reasons we have to believe it is true?

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